JP6210458B2 - Failure detection system and failure detection method - Google Patents

Description

  The present invention relates to a failure detection system and a failure detection method for detecting a failure of a sound collection element.

  There is a strong demand for a high S / N ratio sound collection technique for collecting as much as possible unnecessary sound such as noise and interfering sound when picking up a target sound such as sound. In order to achieve this technique, it is considered that signal processing using a sound collector (microphone array device) composed of a plurality of microphone elements is effective.

  As an example of signal processing using a microphone array device, the sound signal is picked up in a predetermined direction by summing the sound signals after adding different delay times for each microphone element to the sound signals collected by each microphone element. There is a method (delay sum method) for forming the characteristics. In this delay-and-sum method, the directivity control in the signal processing apparatus that performs signal processing is easy, but if it is attempted to obtain directivity for a low frequency, it is necessary to narrow the beam width of the directivity. As a result, the number of arranged elements increases, and as a result, the size of the microphone array device increases.

  In addition to the delay sum method described above, after adding a delay time to the audio signal, the audio signals are subtracted to form a blind spot (low sensitivity) in the noise direction, thereby forming the directivity of the audio in a predetermined direction. There is a method (delay difference method). A microphone array apparatus using such a delay difference method automatically forms a directivity characteristic corresponding to the surrounding noise environment, and is therefore called an adaptive microphone array apparatus.

  The principle of directivity formation in the adaptive microphone array apparatus is as follows (see, for example, Non-Patent Document 1). The adaptive microphone array apparatus geometrically calculates the time difference when the sound signal in the target direction is picked up by each microphone, using the arrival direction of the target sound signal and the arrangement position of each microphone. The adaptive microphone array device adds a delay amount corresponding to this time difference to the audio signal collected by each microphone. As a result, the audio signal is in-phase with the target direction. In addition, the adaptive microphone array apparatus cancels the audio signals in the target direction by taking the difference between the adjacent audio signals among the in-phase audio signals, and includes a signal including only a plurality of adjacent noises (noise signal). ) Is obtained. The adaptive microphone array device passes the adaptive filter for each noise signal and then subtracts each adaptive filter output from the delay output of the first microphone to suppress ambient noise and directivity in the target direction. Is obtained.

Co-authored by Oga, Yamazaki, and Kaneda "Sound System and Digital Processing" Co., Ltd. Publishing, March 25, 1995, P190 (Griffith-Jim adaptive microphone array)

  In the adaptive microphone array apparatus using the delay difference method described in Non-Patent Document 1, if characteristic deterioration or failure occurs in any of the microphone elements, the difference result of the audio signal is affected, and the ambient noise In some cases, an audio signal in the target direction in which noise is suppressed cannot be obtained, and directivity formation accuracy may deteriorate.

  For this reason, the adaptive microphone array device using the delay difference method monitors the characteristics of the microphone element and the circuit that amplifies the sound signal collected by the microphone element during use, and the characteristics of all the microphone elements are aligned. It is necessary to confirm that.

  However, when the directivity is to be formed in an arbitrary direction using the microphone array device, in Non-Patent Document 1, it is premised that the characteristics of all microphone elements are uniform before actual use. It is not considered that the characteristic deterioration or failure of the microphone element occurs during actual use. For this reason, for example, if there is a characteristic deterioration or failure of the microphone element during actual use, it is considered that the accuracy of forming the directivity of sound from the microphone array device in a specific direction deteriorates.

  In view of the above-described conventional situation, the present invention monitors the characteristics of each microphone element included in the microphone array device even during actual use, and an abnormality occurs even if an abnormality occurs in the microphone element. It is an object of the present invention to provide a failure detection system and a failure detection method that specify a microphone element and suppress deterioration in accuracy of directivity formation of sound in a predetermined direction.

The present invention includes a sound collection unit including a plurality of sound collection elements, a first calculation unit for calculating, for each sound collection element, an average power of sound propagated from a sound source to each of the sound collection elements, and the sound collection unit. A second calculation unit that calculates the total average power of the sound propagated to the plurality of usable sound collection elements included in the unit, and a difference between the average power for each of the sound collection elements and the total average power is a predetermined value. A failure determination unit that determines whether there is an unusable malfunctioning sound pickup element based on a comparison result of whether or not the range is exceeded, and the first calculation unit includes a predetermined time interval. sampling the audio picked up by the microphone element in each, that to calculate the average power of the sound collected by the sound collecting device for each of the sound collection device, a fault detection system.

In addition, the present invention is a failure detection method in a failure detection system having a sound collection unit including a plurality of sound collection elements, wherein an average power of sound propagated from a sound source to each of the sound collection elements is calculated as the sound collection element. A step of calculating for each sound, a step of calculating a total average power of the sound propagated to the plurality of usable sound collection elements included in the sound collection unit, an average power for each of the sound collection elements and the total average based difference comparison result whether exceeding a predetermined range and power, possess determining whether there is the sound pickup device in an unusable failure, the average power of the speech In the step of calculating, the sound collected by the sound collection element is sampled at predetermined time intervals, and the average power of the sound collected by the sound collection element is calculated for each sound collection element . This is a failure detection method.

  According to the present invention, even during actual use, the characteristics of each microphone element included in the microphone array device are monitored, and even when an abnormality occurs in the microphone element, the microphone element in which the abnormality has occurred is identified. It is possible to suppress deterioration of the directivity formation accuracy of the voice in a predetermined direction.

The block diagram which shows the system configuration | structure of the failure detection system of 1st Embodiment. (A)-(E) External view of omnidirectional microphone array device Explanatory drawing of an example of the principle which forms directivity in direction (theta) with respect to the sound picked up by the omnidirectional microphone array device Block diagram showing the internal configuration of the omnidirectional microphone array device Block diagram showing internal configuration of signal processor and memory (A), (B) The figure explaining the method of the error detection process which an omnidirectional microphone array apparatus performs Flowchart for explaining an operation procedure of error detection processing in the omnidirectional microphone array apparatus Flowchart explaining operation procedure of directivity forming operation and error detection processing in directivity control device (A), (B) The figure explaining the method of the error detection process in a directivity control apparatus The flowchart explaining the operation | movement procedure of the error detection process of the audio | voice signal in step S23 shown in FIG. Flowchart for explaining the operation procedure of the audio signal error detection process in step S23 following FIG. (A) The figure which shows the screen of a display apparatus, (B) The figure which shows the icon of the patrol lamp displayed on the screen of a display apparatus (A) The figure which shows the screen of a display apparatus, (B) The figure which shows the pop-up window displayed on the screen of a display apparatus (A) The figure which shows operation which performs log display on the screen of the display device, (B) The figure which shows a part of screen of the display device where log display was done (A) Block diagram showing the internal configuration of the omnidirectional microphone array apparatus in the second embodiment, (B) Diagram showing the structure of a voice packet PKT transmitted from the omnidirectional microphone array apparatus Flowchart explaining operation procedure of directivity formation operation and error detection processing in directivity control device The flowchart explaining the operation | movement procedure of the directivity formation operation | movement and error detection processing in the directivity control apparatus of 3rd Embodiment.

  Embodiments of a failure detection system and a failure detection method according to the present invention will be described below with reference to the drawings. The failure detection system of each embodiment is applied to a monitoring system (including a manned monitoring system and an unmanned monitoring system) installed in, for example, a factory, a public facility (for example, a library, an event venue), or a store (for example, a retail store or a bank). Is done.

(First embodiment)

  FIG. 1 is a block diagram illustrating a system configuration of a failure detection system 10 according to the first embodiment. The failure detection system 10 shown in FIG. 1 includes an omnidirectional microphone array device 2, a camera device C11, a directivity control device 3, and a recorder device 4. The omnidirectional microphone array apparatus 2 collects sound in a sound collection area where the failure detection system 10 is installed, and for example, collects sound emitted by a person as an example of a sound source existing in the sound collection area.

  The casing shape of the omnidirectional microphone array apparatus 2 of the present embodiment is described by exemplifying the shape of a disk, but is not limited to the shape of a disk, and is, for example, a donut shape or a ring shape (FIG. 2A to FIG. 2). (See (E)).

  In the omnidirectional microphone array device 2, a plurality of microphone units 22 and 23 are arranged concentrically along the circumferential direction of a disk-shaped housing 21, for example (see FIG. 2A). For the microphone units 22 and 23, for example, high sound quality small electret condenser microphones (ECM: Electret Condenser Microphone) are used. The use of ECM is the same in the following embodiments.

  In the failure detection system 10 shown in FIG. 1, the omnidirectional microphone array apparatus 2, the directivity control apparatus 3, and the recorder apparatus 4 are connected to each other via a network NW. The network NW may be a wired network (for example, an intranet or the Internet) or a wireless network (for example, a wireless LAN (Local Area Network)). The network NW is the same in the following embodiments.

  A camera device C11 as an example of an imaging unit is fixedly installed on a ceiling surface of an event venue, for example. The camera device C11 performs image data (that is, omnidirectional image data) indicating omnidirectional video in the sound collection area, or planar image data generated by performing panoramic conversion by performing a predetermined distortion correction process on the omnidirectional image data. And transmitted to the directivity control device 3 or the recorder device 4 via the network NW. In response to an instruction from the operation unit 32, the directivity control device 3 causes the image signal processing unit 35 to zoom up the image at the designated position and display it on the display device 36.

  When an arbitrary position is designated by the user in the image displayed on the display device 36, the camera device C11 receives the coordinate data of the designated position in the image from the directivity control device 3, and from the camera device C11. Directivity is calculated by calculating data of distance and direction (including horizontal and vertical angles; the same applies hereinafter) to a voice position in real space (hereinafter simply referred to as “voice position”) corresponding to the designated position. It transmits to the control apparatus 3. Note that the distance and direction data calculation processing in the camera device 1 is a known technique, and thus the description thereof is omitted.

  An omnidirectional microphone array apparatus 2 as an example of a sound collection unit is connected to a network NW, and microphone elements 221, 222,..., 22n (see FIG. 3) as examples of sound collection elements arranged at equal intervals. And at least each unit that performs predetermined signal processing on the sound data of the sound collected by each microphone element. The detailed configuration of the omnidirectional microphone array apparatus 2 will be described later with reference to FIG.

  The omnidirectional microphone array apparatus 2 is an example of a voice data packet (packet PKT (see FIG. 15B)) including voice data of voices picked up by the respective microphone units 22 and 23 (see FIG. 2A). ) Is transmitted to the directivity control device 3 or the recorder device 4 via the network NW.

The directivity control device 3 uses the audio data transmitted from the omnidirectional microphone array device 2 to direct in a directivity direction (see below) corresponding to a position (designated position) designated by the operation unit 32 by a user operation. , 22n (see FIG. 3), the sound velocity Vs of the sound propagated from the sound source to each of the microphone elements 221, 222,..., 22n (see FIG. 3) and a different delay time for each microphone element (see FIG. 3) The directivity of the audio data is formed in the directivity direction (θ _MAh , θ _MAv ) that is

As a result, the directivity control device 3 makes the volume level of the sound collected from the directivity direction (θ _MAh , θ _MAv ) where the directivity is formed relatively to the volume level of the sound collected from the other direction. Can be increased. In addition, since the calculation method of directivity direction ((theta) _MAh , (theta) _MAv ) is a well-known technique, detailed description is abbreviate _| omitted in this embodiment.

  The microphone units 22 and 23 of the omnidirectional microphone array apparatus 2 may be omnidirectional microphones, bi-directional microphones, unidirectional microphones, or combinations thereof.

  Further, the camera device C11 is not limited to an omnidirectional camera that captures images in all directions, but may be any camera that has a pan / tilt / zoom function or a fixed camera that can capture an image at a position to be monitored. In this case, a plurality of cameras may be combined instead of one.

  2A to 2E are external views of the omnidirectional microphone array devices 2A, 2B, 2C, 2D, and 2E. The omnidirectional microphone array devices 2A, 2B, 2C. In 2D and 2E, the appearance and the arrangement of a plurality of microphone units are different, but the functions of the omnidirectional microphone array device are the same. In addition, when it is not necessary to distinguish these omnidirectional microphone array apparatuses in particular, they are collectively referred to as an omnidirectional microphone array apparatus 2.

  An omnidirectional microphone array apparatus 2A shown in FIG. 2 (A) has a disk-shaped casing 21. A plurality of microphone units 22 and 23 are concentrically arranged in the housing 21. Specifically, the plurality of microphone units 22 are arranged concentrically along a large circular shape having the same center as the casing 21, and the plurality of microphone units 23 are small having the same center as the casing 21. They are arranged concentrically along a circular shape. The plurality of microphone units 22 have a wide interval, a large diameter, and characteristics suitable for a low sound range. On the other hand, the plurality of microphone units 23 are narrow in distance from each other, have a small diameter, and have characteristics suitable for a high sound range.

  An omnidirectional microphone array apparatus 2B shown in FIG. 2B has a disk-shaped casing 21. In the housing 21, a plurality of microphone units 22 are arranged on a straight line at uniform intervals so that the centers of the vertical and horizontal directions in the horizontal direction intersect at the center of the housing 21. In the omnidirectional microphone array device 2B, since the plurality of microphone units 22 are arranged in a vertical and horizontal straight line, the amount of calculation of the sound data directivity forming process can be reduced. A plurality of microphone units 22 may be arranged in only one column in the vertical direction or the horizontal direction.

  The omnidirectional microphone array apparatus 2C shown in FIG. 2C has a disk-shaped casing 21C having a smaller diameter than the omnidirectional microphone array apparatus 2A shown in FIG. In the casing 21C, a plurality of microphone units 22 are uniformly arranged along the circumferential direction. The omnidirectional microphone array apparatus 2C shown in FIG. 2C has characteristics suitable for a high sound range because the distance between the microphone units 22 is short.

  An omnidirectional microphone array device 2D shown in FIG. 2D has a donut-shaped or ring-shaped housing 21D in which an opening 21a having a predetermined diameter is formed at the center of the housing. In the housing 21D, a plurality of microphone units 22 are arranged concentrically at regular intervals in the circumferential direction of the housing 21D.

  An omnidirectional microphone array apparatus 2E shown in FIG. 2E has a rectangular casing 21E. In the casing 21E, a plurality of microphone units 22 are arranged at uniform intervals along the outer peripheral direction of the casing 21E. In the omnidirectional microphone array apparatus 2E shown in FIG. 2E, since the casing 21E is formed in a rectangular shape, installation of the omnidirectional microphone array apparatus 2E can be simplified even in places such as corners.

  The directivity control device 3 is connected to the network NW, and may be a stationary PC (Personal Computer) installed in a monitoring system control room (not shown), or a mobile phone, tablet terminal, or smart phone that can be carried by the user. A data communication terminal such as

  The directivity control device 3 includes at least a communication unit 31, an operation unit 32, a signal processing unit 33, a display device 36, a speaker device 37, and a memory 38. In FIG. 1, the signal processing unit 33 includes at least a directivity direction calculation unit 34a and an output control unit 34c, and a detailed configuration example of the signal processing unit 33 will be described later with reference to FIG.

  The communication unit 31 receives the packet PKT (see FIG. 15B) transmitted from the omnidirectional microphone array device 2 or the recorder device 4 via the network NW and outputs the packet PKT to the signal processing unit 33.

  The operation unit 32 is a user interface (UI) for notifying the content of a user operation to the signal processing unit 33, and is, for example, a pointing device such as a mouse or a keyboard. In addition, the operation unit 32 may be configured using, for example, a touch panel or a touch pad that is arranged corresponding to the screen of the display device 36 and can be operated by a user's finger or stylus pen.

  The operation unit 32 outputs an image displayed on the display device 36 (i.e., an image captured by the camera device C <b> 11, the same applies hereinafter) specified by a user operation (i.e., the speaker device 37). The coordinate data indicating the position where the increase or decrease of the sound volume level is desired is acquired and output to the signal processing unit 33.

  The signal processing unit 33 is configured using, for example, a CPU (Central Processing Unit), an MPU (Micro Processing Unit), or a DSP (Digital Signal Processor), and is used for overall control of operations of each unit of the directivity control device 3. Control processing, data input / output processing between other units, data calculation (calculation) processing, and data storage processing are performed.

The directivity direction calculation unit 34a coordinates (θ _MAh) indicating the directivity direction from the omnidirectional microphone array device 2 to the sound position corresponding to the specified position in accordance with the user's position specifying operation from the image displayed on the display device 36. , Θ _MAv ). Since the specific calculation method of the pointing direction calculation unit 34 is a known technique as described above, detailed description thereof is omitted.

The directivity direction calculation unit 34a uses the distance and direction data from the installation position of the camera device C11 to the audio position to _{specify the} directivity direction coordinates (θ _MAh , θ) from the installation position of the omnidirectional microphone array device 2 to the audio position. _MAv ) is calculated. For example, when the housing of the omnidirectional microphone array device 2 and the camera device C11 are integrally attached so as to surround the housing of the camera device C11, the direction from the camera device C11 to the sound position (horizontal angle, (Vertical angle) can be used as the directivity direction coordinates (θ _MAh , θ _MAv ) from the omnidirectional microphone array device 2 to the sound position.

When the housing of the camera device C11 and the housing of the omnidirectional microphone array device 2 are mounted apart from each other, the directivity direction calculation unit 34a includes calibration parameter data calculated in advance, Using the data of the direction (horizontal angle and vertical angle) from the device C11 to the voice position, the directivity direction coordinates (θ _MAh , θ _MAv ) from the omnidirectional microphone array device 2 to the voice position are calculated. The calibration is an operation for calculating or obtaining a predetermined calibration parameter necessary for the directivity direction calculation unit 34a of the directivity control device 3 to calculate coordinates (θ _MAh , θ _MAv ) indicating the directivity direction. It is assumed that this is performed in advance by a known technique.

Coordinates indicating the pointing direction (θ _MAh, θ _MAv) of, theta _MAh represents the horizontal angle of orientation toward the sound position from the omnidirectional microphone array apparatus 2, theta _MAv the sound position from the omnidirectional microphone array apparatus 2 Represents the vertical angle of the pointing direction. The voice position is a position on the site that is an actual monitoring target or a sound collection target corresponding to a designated position designated by the user's finger or stylus pen in the image displayed on the display device 36 by the operation unit 32.

The output control unit 34c controls the operations of the display device 36 and the speaker device 37, and displays the image data transmitted from the camera device C11 on the display device 36, for example, in accordance with a user operation, so that the omnidirectional microphone array device 2 Audio data included in a packet PKT (for example, an audio data packet) transmitted from the speaker device 37 is output from the speaker device 37. In addition, the output control unit 34c as an example of the directivity forming unit has an omnidirectional microphone in the directional direction indicated by the coordinates (θ _MAh , θ _MAv ) calculated by the directional direction calculating unit 34a from the omnidirectional microphone array device 2. The directivity of the sound data collected by the array device 2 is formed, but the directivity may be formed in the omnidirectional microphone array device 2.

  The display device 36 as an example of the display unit displays, for example, image data transmitted from the camera device C11 on the screen under the control of the output control unit 34c, for example, according to a user operation.

The speaker device 37 as an example of the audio output unit is directed to the audio data included in the packet PKT transmitted from the omnidirectional microphone array device 2 or the directivity direction (θ _MAh , θ _MAv ) calculated by the directivity direction calculation unit 34a. Audio data in which sex is formed is output. The display device 36 and the speaker device 37 may be configured separately from the directivity control device 3.

  The memory 38 as an example of the storage unit is configured by using, for example, a RAM (Random Access Memory), functions as a work memory during operation of each unit of the directivity control device 3, and further, stores each unit of the directivity control device 3. Data necessary for operation is stored.

  The recorder device 4 as an example of an audio recording unit stores audio data included in the packet PKT transmitted from the omnidirectional microphone array device 2 and image data transmitted from, for example, the camera device C11 in association with each other. Further, an error notification packet transmitted from the omnidirectional microphone array apparatus 2 is also recorded as a log. Since the failure detection system 10 shown in FIG. 1 includes a plurality of camera devices, the recorder device 4 uses the image data transmitted from each camera device and the packet PKT transmitted from the omnidirectional microphone array device 2. The audio data included may be stored in association with each other.

  The recorder device 4 sends an error notification packet from the omnidirectional microphone array device 2 to the audio data packet during recording (in other words, while recording the packet PKT of the audio data transmitted from the omnidirectional microphone array device 2). As an example of an illuminating unit provided on the front surface of the casing of the recorder device 4 when received separately from the PKT, or when receiving a packet PKT of audio data storing information on a malfunctioning microphone element The LED (not shown) blinks or is displayed on an LCD (not shown) as an example of a display unit provided on the front surface of the casing of the recorder device 4. Thereby, the recorder apparatus 4 can notify an operator visually that there exists a malfunctioning microphone element.

  Further, the recorder device 4 receives the error recovery packet from the omnidirectional microphone array device 2 during the recording (in other words, while recording the packet PKT of the audio data transmitted from the omnidirectional microphone array device 2). When receiving the packet PKT of the audio data storing the information on the restored (recovered) microphone element, the LED (provided on the front surface of the casing of the recorder device 4) is received. Flashing (not shown) or display on the LCD (not shown) provided on the front surface of the casing of the recorder device 4 is stopped. Thus, the recorder device 4 can visually notify the operator that there is a restored (recovered) microphone element.

  FIG. 3 is an explanatory diagram of an example of the principle of forming directivity in the direction θ with respect to the sound collected by the omnidirectional microphone array apparatus 2. In FIG. 3, for example, the principle of directivity formation processing using the delay sum method will be briefly described. However, the present embodiment is limited to the case where directivity formation processing using the delay sum method shown in FIG. 3 is performed. Instead, for example, directivity formation processing using the delay difference method shown in Non-Patent Document 1 described above may be performed.

In FIG. 3, the sound wave emitted from the sound source 80 is applied to the microphone elements 221, 222, 223,..., 22 (n-1), 22n built in the microphone units 22, 23 of the omnidirectional microphone array apparatus 2. Incident light is incident at a certain angle (incident angle = (90−θ) [degrees]). The incident angle θ shown in FIG. 3 may be the horizontal angle θ _MAh or the vertical angle θ _MAv in the sound collection direction from the omnidirectional microphone array apparatus 2 toward the sound position.

  The sound source 80 is, for example, a subject of a camera device that exists in a direction in which the omnidirectional microphone array device 2 collects sound, and exists in a direction of a predetermined angle θ with respect to the surface of the casing 21 of the omnidirectional microphone array device 2. . Further, the distance d between the microphone elements 221, 222, 223,..., 22 (n−1), 22n is constant.

  The sound wave emitted from the sound source 80 first reaches (propagates) the microphone element 221 and is collected, then reaches the microphone element 222 and is collected, and similarly collected one after another, and finally the microphone element 22n. Sound is collected after reaching.

  The direction from the position of each microphone element 221, 222, 223,..., 22 (n-1), 22n of the omnidirectional microphone array apparatus 2 toward the sound source 80 is determined from each microphone element of the omnidirectional microphone array apparatus 2. The direction is the same as the direction toward the audio position corresponding to the designated position designated on the screen of the display device 36 by the user.

  Here, there is an arrival time difference τ1, τ2, τ3 from the time when the sound wave reaches the microphone elements 221, 222, 223,..., 22 (n−1) to the time when the sound wave finally reaches the microphone element 22n. ,..., Τn−1 are generated. For this reason, when the sound data collected by the microphone elements 221, 222, 223,..., 22 (n−1), 22n are added as they are, they are added while being out of phase. The volume level weakens overall.

  Note that τ1 is a difference time between the time when the sound wave reaches the microphone element 221 and the time when the sound wave reaches the microphone element 22n, and τ2 is the time when the sound wave reaches the microphone element 222 and the sound wave reaches the microphone element 22n. Similarly, τn−1 is the difference time between the time when the sound wave reaches the microphone element 22 (n−1) and the time when the sound wave reaches the microphone element 22n.

  In the directivity forming process of the present embodiment, A / D converters 241, 242, 243,..., 24 (corresponding to the microphone elements 221, 222, 223,..., 22 (n−1), 22n are provided. In n-1) and 24n, the analog audio signal is converted into a digital audio signal. Further, the digital audio signal is transmitted from the delay elements 251, 252, 253,..., 25 (n−1), 22n, 22n,. A predetermined delay time is added at 25n. The outputs of the delay units 251, 252, 253,..., 25 (n−1), 25 n are added by the adder 39.

  When directivity formation processing is performed in the omnidirectional microphone array apparatus 2, the delay units 251, 252, 253,..., 25 (n-1), 25n are provided in the omnidirectional microphone array apparatus 2 and are directed. When the directivity forming process is performed in the directivity control device 3, the delay units 251, 252, 253,..., 25 (n−1), 25 n are provided in the directivity control device 3.

  Further, in the directivity forming process shown in FIG. 3, the delay units 251, 252, 253,..., 25 (n−1), 25n are respectively connected to the microphone elements 221, 222, 223,. , 22n, a delay time corresponding to the arrival time difference is added and the phases of all the sound waves are aligned and in-phased, and the adder 39 adds the audio data after the delay processing. Thereby, the omnidirectional microphone array device 2 or the directivity control device 3 makes the direction of the angle θ with respect to the sound collected by the microphone elements 221, 222, 223,..., 22 (n−1), 22n. Directivity can be formed.

  For example, in FIG. 3, the delay times D1, D2, D3,..., D (n-1), Dn given in the delay units 251, 252, 253,. This corresponds to the time differences τ1, τ2, τ3,..., Τ (n−1), and is expressed by Equation (1).

  L1 is a difference in sound wave arrival distance between the microphone element 221 and the microphone element 22n. L2 is a difference in sound wave arrival distance between the microphone element 222 and the microphone element 22n. L3 is a difference in sound wave arrival distance between the microphone element 223 and the microphone element 22n. Similarly, L (n-1) is a difference in sound wave arrival distance between the microphone element 22 (n-1) and the microphone element 22n. It is. Vs is the speed of sound waves. The sound velocity Vs may be calculated by the omnidirectional microphone array device 2 or by the directivity control device 3 (see later). L1, L2, L3,..., L (n−1) are known values. In FIG. 3, the delay time Dn set in the delay device 25n is 0 (zero).

  In the directivity forming process, the delay time Di (i = 1 to n, where n is an integer equal to or greater than 2) given to the sound data of the sound collected by each microphone element is expressed by Equation (1). Is inversely proportional to the speed of sound Vs.

  As described above, the omnidirectional microphone array device 2 or the directivity control device 3 has the delay times D1, D2, D3,... Provided in the delay units 251, 252, 253,. By changing Dn-1 and Dn, the sound of the sound collected by each microphone element 221, 222, 223, ..., 22 (n-1), 22n built in the microphone unit 22 or the microphone unit 23 Data directivity can be easily and arbitrarily formed.

  FIG. 4 is a block diagram showing the internal configuration of the omnidirectional microphone array apparatus 2. An omnidirectional microphone array apparatus 2 shown in FIG. 4 includes a plurality (n, for example, n = 16) of microphone elements 22i, n amplifiers (amplifiers) 28i that amplify output signals of the microphone elements 22i, and amplifiers. The configuration includes n A / D converters 24 i that convert analog signals output from 28 i into digital signals, an encoding unit 25, a detection unit 29, an error packet generation unit 27, and a transmission unit 26. is there. Here, the subscript i of the microphone element 22i is the number of the microphone element, which is 1 to n (total number of microphone elements), and the same applies to the amplifier 28i and the A / D converter 24i.

  The encoding unit 25 encodes the digital audio signal (audio data) output from the n A / D converters 24i. The detection unit 29 as an example of a failure determination unit performs failure detection for each microphone element 22 i using the audio data encoded by the encoding unit 25.

  When the detection unit 29 determines that any of the microphone elements is in failure, the error packet generation unit 27 generates an error notification packet including information on the microphone element in failure. Further, the error packet generation unit 27 recovers (restores) the microphone element determined to be in failure due to, for example, repair / inspection work (for example, when the acoustic characteristic of the microphone element becomes a desired characteristic) ) Generates an error recovery packet including information on the recovered microphone element. As described above, an identification number (microphone ID) for identifying a microphone element is added to the error notification packet and the error recovery packet.

  The transmission unit 26 generates a packet PKT of encoded audio data and transmits the packet PKT to the directivity control device 3 or the recorder device 4 that is recording. The transmission unit 26 transmits the error notification packet and the error recovery packet to the directivity control device 3 or the recorder device 4 that is recording. Note that the transmission unit 26 may add the information regarding the failed or recovered microphone element to the voice data packet PKT and then transmit the packet to the directivity control device 3 or the recording device 4 during recording.

  FIG. 5 is a block diagram showing the internal configuration of the signal processing unit 33 and the memory 38. The signal processing unit 33 illustrated in FIG. 5 includes a directivity direction calculation unit 34a, an output control unit 34c, an FFT unit 331, three failure detection units 340, 350, and 360, a directivity processing unit 335, and the like. The configuration includes an FFT unit 336 and a determination unit 337. In FIG. 5, illustration of the directivity direction calculation unit 34 a and the output control unit 34 c is omitted for the sake of simplicity.

  An FFT (Fast Fourier Transform) unit 331 performs Fourier transform on the input time axis signal, and converts the time axis signal of the audio data into a frequency axis signal. The output of the FFT unit 331 is input to the three failure detection units 340, 350, and 360 and the directivity processing unit 335.

  The failure detection unit 340 includes a smoothing unit 341, a comparison unit 342, an average calculation unit 343, and a result holding unit 345. Since the configurations of the failure detection units 340, 350, and 360 are the same, for example, the failure detection unit 340 will be described as an example, and the same content common to the three failure detection units 340, 350, and 360 will be described. Are simplified or omitted, and different contents will be described.

  Of the outputs from the FFT unit 331, the failure detection unit 340 receives a signal having a frequency component in a predetermined range centered on, for example, 250 Hz. In addition, the failure detection unit 350 receives a signal having a frequency component in a predetermined range centered on, for example, 1 kHz among the outputs of the FFT unit 331. Similarly, out of the output of the FFT unit 331, for example, a signal having a frequency component in a predetermined range centered on 4 kHz is input to the failure detection unit 360.

  The smoothing unit 341 calculates and smoothes the sound pressure level (acoustic power) using the sampling result of one frame (for example, 256) of the sound signal output from the microphone element 22i, thereby smoothing the average sound of the sound signal. Power (hereinafter simply referred to as “average power”) is obtained for each microphone element 22i.

  The average calculation unit 343 smoothes the average power of all the microphone elements that can be used (in other words, not in failure) among all the microphone elements of the omnidirectional microphone array apparatus 2, so that the total average sound of the audio signal is obtained. Power (hereinafter simply referred to as “total average power”) is calculated.

  The comparison unit 342 determines whether or not the difference between the average power of the microphone elements to be inspected for failure detection and the total average power of all usable microphone elements is within a predetermined range (for example, a range of ± 6 dB). Determine. The result holding unit 345 stores the output (comparison result) from the comparison unit 342.

  The directivity processing unit 335 corresponds to the audio data collected by the microphone element 22i and the designated position from the operation unit 32 on the image displayed on the screen of the display device 36 as an example of the processing of the output control unit 34c. The directivity of the voice is formed using the coordinates indicating the directivity direction toward the voice position to be played. In the above description, the directivity processing unit 335 is described as being included as an example of the output control unit 34c. However, the directivity processing unit 335 may be configured as a processing unit in the signal processing unit 33 different from the output control unit 34c. good.

  An inverse FFT (Inverse Fast Fourier Transform) unit 336 outputs the output of the directivity processing unit 335 (that is, a voice frequency axis signal in which voice directivity is formed in the directivity direction) as an example of processing of the output control unit 34c. On the other hand, inverse Fourier transform is performed, and the frequency axis signal of the audio data is converted into a time axis signal and output to the speaker device 37. Although the inverse FFT unit 336 has been described as being included as an example of the output control unit 34c, similarly to the directivity processing unit 335, the inverse FFT unit 336 is configured as a processing unit in the signal processing unit 33 different from the output control unit 34c. May be.

  The determination unit 337 as an example of the failure determination unit is one of the microphone elements 22i based on the comparison results held in the result holding units 345, 355, and 365 of the three failure detection units 340, 350, and 360. It is determined whether or not the device is out of order.

  The memory 38 is configured using, for example, a RAM (Random Access Memory), and includes a usable microphone information holding unit 381 and a log information holding unit 382. The usable microphone information holding unit 381 stores information related to microphone elements that are not in failure (in other words, usable) among all the microphone elements of the omnidirectional microphone array apparatus 2. Note that the usable microphone information holding unit 381 may store information on unusable microphone elements together with information on usable microphone elements.

  The log information holding unit 382 stores the result of the determination unit 337 determining that there is a malfunctioning microphone element.

  Next, operation | movement of the failure detection system 10 of this embodiment is demonstrated with reference to drawings. In the present embodiment, the omnidirectional microphone array device 2 determines whether or not the microphone element 22i has a failure, and the directivity control device 3 also determines whether or not the microphone element 22i has a failure. First, the operation relating to the determination of whether or not the microphone element 22i has a failure in the omnidirectional microphone array apparatus 2 will be described with reference to FIGS. 6 (A) and 6 (B). 6A and 6B are diagrams for explaining a method of error detection processing performed by the omnidirectional microphone array device 2. FIG.

  As shown in FIG. 6A, when the detection unit 29 calculates the average power and the total average power used for detecting the failure of the microphone element 22i, for example, 16 m (16 microphone elements) of audio data for 32 msec is obtained. By sampling at a sampling frequency of 16 kHz, 512 sampling data are acquired. The detection unit 29 uses the first 256 sampling data out of 512 sampling data for the microphone element 22i to be inspected for failure detection, and outputs the power (average power) that is the sound pressure level after smoothing. calculate.

  Further, the detection unit 29 uses the first 256 sampling data among the 512 sampling data for all the microphone elements that are not in failure (in other words, usable) in the omnidirectional microphone array apparatus 2. Then, the average value of the sound pressure level (power) after smoothing is calculated, and the total average power of all microphone elements (for example, 16 microphone elements) is calculated. As described above, the detection unit 29 samples the audio data at a predetermined interval (cycle = 1/16 kHz) and calculates the average power using a lot of sampling data, so that the accuracy of calculating the average power is improved. Can do.

  As shown in FIG. 6 (B), when the failure determination of the microphone element 22i is performed, the detection unit 29 periodically samples the sound data of the 16 microphone elements at intervals of about 1 second to obtain the sampling data. To calculate the average power after smoothing. When the difference between the average power and the total average power of the microphone elements is within a predetermined range (± 6 dB range), the detection unit 29 is normal (indicated by “◯” shown in FIG. 6B). It is determined that there is an error, and if it exceeds the predetermined range, it is determined that there is an error (represented by “x” shown in FIG. 6B). For example, when the detection unit 29 determines that there is an error for five consecutive times as a comparison result, the detection unit 29 determines that the microphone element is in failure. In addition, when the detection unit 29 determines that it is normal even once in the middle of five consecutive times, the detection unit 29 clears the number of errors until it is determined to be normal to 0, and the microphone element is normal. Judge that there is. Moreover, even if the detection unit 29 once determines that the microphone element is in failure, for example, if it is determined that the microphone element is normal five times consecutively as a comparison result, the microphone element is recovered (restored) and is normal. Judge that there is.

  FIG. 7 is a flowchart for explaining an operation procedure of error detection processing in the omnidirectional microphone array apparatus 2. In FIG. 7, a variable p indicates the number of consecutive NGs (number of continuous errors), and a variable m indicates the number of continuous OKs (continuous normal number). Further, the error detection process shown in FIG. 7 is performed for each microphone element. For example, when the total number of microphone elements is 16, the error detection process for all microphone elements is completed when executed 16 times in total.

  First, the detection unit 29 sets the continuous NG number p and the continuous OK number m to the value 0 (S1). The detection unit 29 samples the audio data encoded by the encoding unit 25 (S2). In this sampling, for example, the top 256 sampling data of the sound data of 32 msec is extracted at intervals of 1 second.

  The detection unit 29 calculates average power from 256 pieces of sampling data (S3). Further, the detection unit 29 calculates the average power (total average power) of all channels (that is, all microphone elements) (S4). For example, the detection unit 29 may store the total average power after calculating the average power of each microphone element, and may calculate the average power of all the latest microphone elements. After adding 256 pieces of sampling data, the sampling data after addition may be averaged. The detection unit 29 stores the calculated total average power in a memory (not shown).

  The detection unit 29 reads the total average power stored in the memory (S5), and compares the average power calculated in step S3 with the total average power (S6).

  The detection unit 29 determines whether or not the difference between the average power and the total average power is a predetermined level difference, that is, exceeds a predetermined range (here, as an example, exceeds ± 6 dB) (S7). . When there is no level difference and does not exceed the predetermined range, that is, when it is normal within ± 6 dB (S7, NO), the detection unit 29 determines whether or not an error has been notified (S8). . When no error has been notified (S8, NO), the processing of the detection unit 29 returns to step S2.

  On the other hand, when the error notification has been completed in step S8 (S8, YES), the detection unit 29 increases the value of the continuous OK number m by one (S9). The detection unit 29 determines whether the value of the continuous OK number m has reached 5 (S10). When the value of m is less than 5 (S10, NO), the process of the detection unit 29 returns to step S2. On the other hand, when the value of m is 5 (S10, YES), the error packet generator 27 generates an error recovery packet (S11). As an example in which the process of step S11 occurs, it may be mentioned that the malfunctioning microphone element has been restored to a normal microphone element by replacement or repair by a predetermined worker.

  The transmission unit 26 transmits the error recovery packet generated by the error packet generation unit 27 to the directivity control device 3 or the recording device 4 that is recording (S12). The detection unit 29 clears the value of the continuous OK number m to 0 (S13). After step S13, the process of the detection unit 29 returns to step S2.

  On the other hand, when the difference between the average power and the total average power exceeds the predetermined range in step S7 (S7, YES), the detection unit 29 increases the value of the continuous NG number p by 1 (S14). The detection unit 29 determines whether or not the value of the number of consecutive NGs has become 5 (S15). When the value of p is not 5 (S15, NO), the process of the detection unit 29 returns to Step S2. On the other hand, when the value of p is 5 (S15, YES), the error packet generator 27 generates an error notification packet (S16). The error notification packet includes an alarm notification.

  The transmitting unit 26 transmits the error notification packet generated by the error packet generating unit 27 to the directivity control device 3 or the recording device 4 that is recording (S17). The detection unit 29 clears the value of the continuous NG number p to 0 (S18). After step S18, the process of the detection unit 29 returns to step S2.

  Thus, the omnidirectional microphone array apparatus 2 calculates the average power from the top 256 sampling data of the sound data of 32 msec of each channel (one microphone element) at intervals of about 1 second, for example, and outputs all the channels (here, If the state exceeding the range of ± 6 dB continues for five consecutive times compared to the average value of 16 microphone elements), it is determined that the microphone element used for the comparison is in failure, and an error notification packet is transmitted. The omnidirectional microphone array apparatus 2 can eliminate the error at the time of sound collection that occurs temporarily, for example, by determining that the microphone element is in failure when it continues for five consecutive times. The determination accuracy can be improved. In addition, since the error notification packet is transmitted, the directivity control device 3 can easily identify the sound collection element in failure by the failure data packet. The recorder device 4 records a failure or recovery log of the microphone element by an error notification packet or an error recovery packet, and blinks an LED (not shown) provided in the recorder device 4 to the user, By displaying information on an LCD (not shown) provided in 4, a failure or recovery (recovery) of the microphone element can be notified.

  In addition, even if the microphone element determined to be in error is in the case where the average power is within ± 6 dB for five consecutive times, the omnidirectional microphone array apparatus 2 is recovered by replacing or repairing the microphone element. Determine and send an error recovery packet. Thereby, the omnidirectional microphone array apparatus 2 can easily determine the recovery of the microphone element.

  Next, the operation of the directivity control device 3 will be shown. FIG. 8 is a flowchart for explaining the operation procedure of the directivity forming operation and the error detection process in the directivity control device 3. In FIG. 8, the signal processing unit 33 receives the packet PKT transmitted from the omnidirectional microphone array device 2 or the recorder device 4 via the communication unit 31 (S21). The signal processing unit 33 determines whether a warning (alarm) notification is included in the packet PKT (S22). When the alarm notification is not included (S22, NO), the failure detection units 340, 350, and 360 in the signal processing unit 33 perform audio signal error detection processing (S23). Details of the error detection processing will be described later with reference to FIGS.

  The determination unit 337 in the signal processing unit 33 determines whether or not a failure of the microphone element is detected by the failure detection units 340, 350, and 360 (S24). When a failure is not detected (S24, NO), the directivity processing unit 335 in the signal processing unit 33 reads information on usable microphone elements stored in the usable microphone information holding unit 381 (S25). .

  The directivity processing unit 335 does not use the faulty microphone element, that is, uses the voice data of the faulty microphone element among the frequency axis signals of the voice data fast Fourier transformed by the FFT unit 331. Instead, the sound data of normal microphone elements is used to form the directivity of the sound data with respect to the directivity direction calculated by the directivity direction calculation unit 34a by the operation of the operation unit 32 from the omnidirectional microphone array device 2 ( S26). Thus, the directivity control device 3 can form the directivity of the voice in a specific direction by excluding the malfunctioning microphone element and not using it. It is possible to suppress the deterioration of the sound directivity formation accuracy.

  The inverse FFT unit 336 performs inverse Fourier transform on the frequency axis signal of the audio data on which directivity is formed, and outputs a time axis signal of the audio data. Thereby, a sound is output from the speaker device 37 (S27). Thereby, the operation of the signal processing unit 33 ends.

  On the other hand, when a failure of the microphone element is detected in step S24 (S24, YES), the determination unit 337 outputs an error notification to the display device 36 (S30). An identification number for identifying the microphone element is added to this error notification. The determination unit 337 records (saves) the error log in the log information holding unit 382 in the memory 38 (S31). Further, the determination unit 337 updates the information on the usable microphone elements stored in the usable microphone information holding unit 381 (S32). Thereafter, the processing of the signal processing unit 33 proceeds to step S25.

  In step S <b> 22, when the packet received from the omnidirectional microphone array device 2 includes an alarm (alarm) notification (S <b> 22, YES), the signal processing unit 33 sends the signal processing unit 33 to the display device 36. On the other hand, an error notification is output (S28). An identification number for identifying the microphone element is added to this error notification. By this error notification, as will be described later, a patrol lamp icon 41 (see FIG. 12B) is displayed on the screen of the display device 36. The signal processing unit 33 records (saves) the error log in the log information holding unit 382 in the memory 38 (S29). Thereafter, the processing of the signal processing unit 33 returns to step S21.

  FIGS. 9A and 9B are diagrams for explaining a method of error detection processing in the directivity control device 3. On the directivity control device 3 side, determination processing for determining whether there is a failure of the microphone element is performed at three specific frequencies (for example, 250 Hz, 1 kHz, 4 kHz). The failure detection units 340, 350, and 360 perform determination processing for the presence or absence of a failure of the microphone element using the audio data of 250 Hz, 1 kHz, and 4 kHz, respectively, and detect the failure except for the difference in frequency that is the target of the determination processing. The operation of failure determination in the units 340, 350, 360 is the same.

  As shown in FIG. 9A, the failure detection unit 340 calculates the average power of each microphone element by using the top 256 sampling data of 250 Hz by the same method as in FIG. Further, the failure detection unit 340 calculates the total average power obtained by averaging the average power of each microphone element. The failure detection unit 340 is normal (“◯” shown in FIG. 9B) when the difference between the average power and the total average power of each microphone element is within a predetermined range (± 6 dB range). If it exceeds the predetermined range, it is determined that an error has occurred (represented by “x” shown in FIG. 9B).

  Similarly, the failure detection unit 350 calculates the average power and the total average power of each microphone element using the first 256 sampling data of 1 kHz, and similarly calculates the difference between the average power and the total average power and a predetermined value. And the range (± 6 dB range). Similarly, the failure detection unit 360 calculates the average power and total average power of each microphone element using the top 256 sampling data of 4 kHz, and similarly calculates the difference between the average power and the total average power. A predetermined range (± 6 dB range) is compared.

  As shown in FIG. 9B, the failure detection unit 340 performs the determination process of the presence / absence of a failure at intervals of a predetermined period (for example, about 12.5 seconds). The failure detection unit 340 compares the difference between the average power and the total average power with a predetermined range (± 6 dB range) using the audio sampling data (250 Hz) of the microphone element to be inspected for failure detection. . Failure detection unit 340 determines that the difference between the average power and the total average power is normal (represented by “◯” shown in FIG. 9B) when the difference is within a predetermined range (± 6 dB range). On the other hand, if it exceeds the predetermined range, it is determined that an error has occurred (represented by “x” shown in FIG. 9B). The failure detection unit 340 repeats this comparison every period of about 12.5 seconds. The failure detection unit 340 determines that the microphone element is in failure when the total number of errors indicates 80% or more within a period of about 12.5 seconds. In the next period of about 12.5 seconds, the failure detection unit 340 performs the same operation with the next microphone element as an inspection target.

  Moreover, the failure detection unit 350 compares the difference between the average power and the total average power with a predetermined range (± 6 dB range) using the sampling data (1 kHz) of the sound of the microphone element to be inspected, The same operation is performed. Further, the failure detection unit 360 uses the sampling data (4 kHz) of the sound of the microphone element to be inspected, and compares the difference between the average power and the total average power with a predetermined range (± 6 dB range), The same operation is performed.

  FIG. 10 is a flowchart for explaining the audio signal error detection processing procedure in step S23 shown in FIG. FIG. 11 is a flowchart for explaining the operation procedure of the audio signal error detection processing in step S23 following FIG.

  In FIG. 10, first, the contents of each result holding unit 345, 355, 365 are cleared (S41-B). Next, the signal processing unit 33 samples the audio data input from the omnidirectional microphone array device 2 via the communication unit 31 (S41). The FFT unit 331 performs fast Fourier transform processing on the audio data, and divides the frequency axis signal of the audio data into the above-described three specific frequencies of 250 Hz, 1 kHz, and 4 kHz (S42). These three frequencies are examples, and other frequencies may be used regardless of the audible range.

  In the case of 250 Hz audio data, the smoothing unit 341 in the failure detection unit 340 smoothes the power (sound pressure level) of each microphone element and calculates the average power (S43). Further, the average calculation unit 343 calculates the total average power by averaging the powers of all the microphone elements that can be used (in other words, not in failure) including the microphone element to be inspected (S44).

  The comparison unit 342 reads the total average power calculated by the average calculation unit 343 (S45) and compares it with the average power of the microphone element to be inspected (S46). The comparison unit 342 stores the comparison result in the result holding unit 345 (S47). Thereafter, the processing of the signal processing unit 33 proceeds to step S58.

  In the case of 1 kHz audio data, the smoothing unit 351 in the failure detection unit 350 smoothes the power (sound pressure level) of each microphone element and calculates the average power (S48). Further, the average calculating unit 353 calculates the total average power by averaging the powers of all the microphone elements that can be used (in other words, not in failure) including the microphone element to be inspected (S49).

  The comparison unit 352 reads the total average power calculated by the average calculation unit 343 (S50) and compares it with the average power of the microphone element to be inspected (S51). The comparison unit 352 stores the comparison result in the result holding unit 355 (S52). Thereafter, the processing of the signal processing unit 33 proceeds to step S58.

  In the case of 4 kHz audio data, the smoothing unit 361 in the failure detection unit 360 smoothes the power (sound pressure level) of each microphone element and calculates the average power (S53). Further, the average calculation unit 363 calculates the total average power by averaging the powers of all the microphone elements that can be used (in other words, not in failure) including the microphone element to be inspected (S54).

  The comparison unit 362 reads the total average power calculated by the average calculation unit 363 (S55) and compares it with the average power of the microphone element to be inspected (S56). The comparison unit 362 stores the comparison result in the result holding unit 365 (S57). Thereafter, the processing of the signal processing unit 33 proceeds to step S58.

  The signal processing unit 33 determines whether or not a comparison result for a certain period (for example, about 12.5 seconds) has been stored (saved) (S58). When the comparison result for a certain period is not stored (S58, NO), the processing of the signal processing unit 33 returns to step S41. On the other hand, when the comparison results for a certain period are stored (S58, YES), the determination unit 337 determines that the number of errors determined as a result of the comparison in the certain period is a predetermined ratio (80% as an example). It is determined whether or not it exceeds (S59).

  For example, when it exceeds a predetermined ratio (for example, 80%, the same applies hereinafter) (S59, YES), the determination unit 337 determines that the microphone element is out of order (S61). Here, the determination unit 337 indicates that the microphone element is out of order when the number determined to be an error exceeds a predetermined ratio (80%) in any frequency band of 250 Hz, 1 kHz, and 4 kHz, for example. However, if it exceeds 80% in all frequency bands, it may be determined that the microphone element is malfunctioning.

  On the other hand, when the ratio is equal to or less than the predetermined ratio (80%) (S59, NO), the determination unit 337 determines that the microphone element is normal. After step S59 or S61, the signal processing unit 33 proceeds to step S24.

  FIG. 12A is a diagram illustrating a screen of the display device 36. On the screen of the display device 36, a pull-down menu list 36A, various operation buttons 36B, a detailed information presentation column 36C, and the like are displayed.

  In the pull-down menu list 36A, menus such as device tree, group, sequence, simple playback, search, download, alarm log, device failure log, etc. are expanded in a pull-down format. The various operation buttons 36B include operation buttons such as zoom, focus, brightness, and preset. Details of the selected information are displayed in the detailed information presentation column 36C.

  FIG. 12B is a diagram showing a patrol lamp icon 41 displayed on the screen of the display device 36. When the communication unit 31 of the directivity control device 3 receives the error notification packet from the omnidirectional microphone array device 2 and the signal processing unit 33 issues an error notification in step S28 described above, the output control unit 34c is connected to the display device 36. The patrol lamp icon 41 blinks in red in the upper right corner of the screen. An operator (a user, the same shall apply hereinafter) can know that a failure has occurred in the microphone element by looking at the patrol lamp icon 41 blinking in red in the upper right corner of the screen.

  Thereafter, when the communication unit 31 of the directivity control device 3 receives the error recovery packet from the omnidirectional microphone array device 2, the output control unit 34c displays the patrol lamp icon 41 blinking in red on the display device 36 in green. Change to blinking display. When the operator clicks the patrol icon 41, the patrol icon 41 disappears.

  FIG. 13A is a diagram showing a screen of the display device 36. FIG. 13B is a diagram showing a pop-up window 36D displayed on the screen of the display device 36. When the directivity control device 3 detects an error and the signal processing unit 33 gives an error notification in the above-described step S30, the output control unit 34c displays a pop-up window 36D that notifies the occurrence of an event at the lower right corner of the screen of the display device 36. Is displayed. In this pop-up window 36D, for example, a message “There is an abnormality in microphone No. 3 2014/04/01 13:45” is displayed. Then, the operator can know that a failure has occurred in the microphone element by looking at the pop-up window displayed in the lower right corner of the screen.

  In addition, there is a log recorded based on the reception of the error notification packet when the patrol lamp icon 41 or the pop-up window 36D is displayed on the screen of the display device 36, or when the data of the recorder device 4 is reproduced. In this case, the operator can display a log relating to the failure of the microphone element (see the functional failure log shown in FIG. 14A) on the screen of the display device 36. FIG. 14A is a diagram illustrating an operation for displaying a log on the screen of the display device 36.

  When the operator clicks and selects the device failure log 36e included in the pull-down menu list 36A, the output control unit 34c expands and displays the device failure log 36e, thereby displaying the device failure log list 36f. .

  FIG. 14B is a diagram illustrating a part of the screen of the display device 36 on which the log display is performed. For example, “2014/04/01 12:25 MIC1 ECM” is displayed as the device failure log. The operator can know the failure of the microphone element by looking at the log.

  The device failure log may be displayed on a separate screen instead of being expanded in the pull-down menu list 36A. Further, as a notification method to the operator, the output control unit 34c may not only display on the display device 36 but also output an alarm sound from the speaker device 37, or automatically to a pre-registered mail address. An e-mail may be transmitted.

  As described above, in the failure detection system 10 of the present embodiment, the omnidirectional microphone array device 2 can easily detect the presence / absence of a failure of the microphone element 22i (for example, compared with an average sound power of 16 msec per second). In addition, an error notification packet including information related to the malfunctioning microphone element or an error recovery packet including information related to the microphone element whose failure has been recovered is transmitted to the directivity control device 3. The directivity control device 3 performs display corresponding to the error notification packet or the error recovery packet. The operator can easily know the failure of the microphone element 22i by blinking the patrol lamp or checking the log.

  The directivity control device 3 always performs failure detection from the average power of 250 Hz, 1 kHz, and 4 kHz without depending on the failure detection result of the omnidirectional microphone array device 2. Thereby, the directivity control device 3 can detect the failure of the microphone element in which an error occurs depending on the specific frequency. Therefore, the directivity control device 3 can monitor the change in the frequency characteristics of the microphone element by monitoring the presence or absence of a failure at a specific frequency, and can detect a failure with high accuracy.

  Further, for example, when an error (abnormality) is 80% or more in any frequency band in 12.5 seconds, the directivity control device 3 determines that the microphone element 22i is in failure. In this way, it is possible to increase the accuracy of failure determination by determining that the microphone element has failed when the frequency of occurrence of errors is high. Further, the ratio may be set so as to be changeable to a value other than 80%, and the failure determination according to the situation becomes possible. Here, the return determination is not performed. The operator can know the failure of the microphone element 22i by displaying a pop-up window or checking the log.

  As a result, the directivity control device 3 monitors the characteristics of the microphone elements mounted on the omnidirectional microphone array apparatus, and the directivity characteristics formed in a predetermined direction are deteriorated even if the microphone elements are abnormal. Can be suppressed.

  It should be noted that simple microphone element failure detection is performed in the omnidirectional microphone array device 2 and the directivity control device 3 may perform highly accurate microphone element failure detection only when a failure is detected. It is also possible to realize an efficient fault detection system by well performing fault detection.

(Second Embodiment)
In the first embodiment, the omnidirectional microphone array apparatus 2 transmits an error notification packet or an error recovery packet separately from the voice data packet. In the second embodiment, an example will be described in which the omnidirectional microphone array apparatus 2G adds and transmits microphone failure data to the header HD of the audio data packet PKT (audio data packet). Further, in the second embodiment, unlike the first embodiment, the directivity control device 3 omits the execution of the detection process for the presence or absence of failure of each microphone element.

  In addition, since the configuration of the failure detection system of the second embodiment has almost the same configuration as that of the first embodiment, the same components as those of the first embodiment are denoted by the same reference numerals, and the description thereof will be given. Is omitted.

  FIG. 15A is a block diagram showing an internal configuration of the omnidirectional microphone array apparatus 2G in the second embodiment. The omnidirectional microphone array apparatus 2G is the same as the omnidirectional microphone array apparatus 2 except that the error packet generation unit 27 is omitted and the output destination of the detection unit 29A is different from that of the omnidirectional microphone array apparatus 2 shown in the first embodiment. If the detection unit 29 </ b> A determines that the microphone element is in failure, the detection unit 29 </ b> A outputs a notification of information regarding the microphone element in failure to the encoding unit 25.

  When receiving the notification of the information regarding the malfunctioning microphone element, the encoding unit 25 stores the information regarding the malfunctioning microphone element as microphone failure data in the header HD of the packet PKT of the audio data. FIG. 15B is a diagram showing the structure of a voice packet PKT transmitted from the omnidirectional microphone array apparatus 2G. The transmission unit 26 transmits the packet PKT including the audio data VD to the directivity control device 3 or the recorder device 4.

  FIG. 16 is a flowchart for explaining the operation procedure of the directivity forming operation and the error detection process performed by the directivity control device 3. In the description of FIG. 16, the same step numbers as those in the first embodiment shown in FIG. The directivity control device 3 has the same configuration as that of the first embodiment. However, as described above, in the second embodiment, execution of the error detection process of the audio signal is omitted.

  In FIG. 16, the signal processing unit 33 of the directivity control device 3 acquires a packet of audio data from the omnidirectional microphone array device 2G or the recorder device 4 via the communication unit 31 (S21A). The determination unit 337 in the signal processing unit 33 determines whether there is microphone failure data in the voice data packet (S24A). When there is microphone failure data (S24A, YES), the process of the determination unit 337 proceeds to step S30, and the same process as in the first embodiment shown in FIG. 8 is performed in steps S30, S31, and S32. On the other hand, when there is no microphone failure data in step S24A (S24A, NO), the process of the determination unit 337 proceeds to step S25, and the same process as in the first embodiment is performed in steps S25, S26, and S27.

  As described above, in the failure detection system 10 according to the present embodiment, only the omnidirectional microphone array device 2G performs the failure determination of the microphone element, so that it is possible to easily determine whether or not there is a failure of the microphone element.

  Further, since the failure detection system 10 adds information (failure data) regarding the microphone element in failure to the packet PKT of the audio data VD, for example, the audio data recorded by the input operation to the operation unit 32 by the operator. Can be omitted, the process of analyzing the error notification log of the packet PKT of the audio data VD transmitted from the omnidirectional microphone array apparatus 2G or the recorder apparatus 4 in detail can be omitted, and the microphone that is out of order can be simplified. Can be identified. In addition, the failure detection system 10 does not need to analyze the log recorded in the recorder device 4 regardless of the point in time when the voice data recorded from the recorder device 4 is played back by a user operation. The presence / absence of an element failure can be easily grasped, and directivity can be formed using a usable sound collecting element.

(Third embodiment)
In the first embodiment, the omnidirectional microphone array device 2 detects a failure of the microphone element 22i. In the third embodiment, the omnidirectional microphone array device 2 does not detect the presence or absence of a microphone element failure by simply transmitting a packet of audio data, and the directivity control device 3 detects the presence or absence of a microphone element failure. An example of processing will be described.

  Since the failure detection system of the third embodiment has almost the same configuration as that of the first embodiment, the same reference numerals are used for the same components as those of the first embodiment, and the description thereof is omitted. .

  FIG. 17 is a flowchart for explaining the operation procedure of the directivity forming operation and the error detection process performed by the directivity control device 3 in the third embodiment. In the description of FIG. 17, the same step numbers are assigned to the same step processes as those of the first embodiment (see FIG. 8) and the second embodiment (see FIG. 16), and the description thereof is omitted.

  In FIG. 17, the signal processing unit 33 of the directivity control device 3 acquires a packet of audio data from the omnidirectional microphone array device 2 (S21B). The failure detection units 340, 350, and 360 in the signal processing unit 33 perform audio signal error detection processing (S23). Since this error detection process is as shown in FIG. 10 and FIG. 11, the description is omitted.

  In step S24, the determination unit 337 in the signal processing unit 33 determines whether the failure detection unit 340, 350, or 360 has detected the presence or absence of a microphone element failure. Thereafter, the processing of steps S25 to S27 and the processing of steps S30 to S32 are the same as the content of the processing of the same step number shown in FIG.

  As described above, in the failure detection system 10 of the present embodiment, the omnidirectional microphone array apparatus 2 omits the execution of the detection process for the presence or absence of the failure of the microphone element 22i. Compared to the omnidirectional microphone array device 2 of the embodiment, the processing load of the omnidirectional microphone array device 2 can be reduced.

  Finally, the configuration, operation, and effect of the failure detection system and failure detection method according to the present invention will be described.

  One embodiment of the present invention includes a sound collection unit including a plurality of sound collection elements, a first calculation unit that calculates, for each sound collection element, an average power of sound propagated from a sound source to each of the sound collection elements, A second calculation unit for calculating the total average power of the sound propagated to the plurality of usable sound collection elements included in the sound collection unit, and the average power and the total average power for each of the sound collection elements A failure detection system comprising: a failure determination unit that determines whether or not there is an unusable failed sound collecting element based on a comparison result of whether or not the difference exceeds a predetermined range.

  In this configuration, the first calculation unit calculates the average power of the sound propagated from the sound source to each sound collection element for each sound collection element. The second calculation unit calculates the total average power of the sound propagated to the plurality of usable sound collection elements included in the sound collection unit. The failure determination unit determines whether or not there is an unusable sound collecting element based on a comparison result of whether or not the difference between the average power and the total average power for each sound collecting element exceeds a predetermined range. judge.

  As a result, even when the failure detection system is actually in use, the acoustic characteristics of each sound collection element included in the sound collection unit (for example, the average value of the individual sound powers of the sound collection elements as the sound power, The average value of the total sound power of a plurality of sound pickup elements that can be used) is monitored, so that for each sound pickup element, the difference between the individual average power and the total average power and the comparison result between the predetermined range and the predetermined range The sound collection element can be specified. Accordingly, the failure detection system suppresses deterioration of the directivity formation accuracy of the sound in a predetermined direction even when the sound collection element included in the sound collection unit is abnormal even during actual use. be able to.

  Further, according to an embodiment of the present invention, the sound collected by a plurality of usable sound collection elements excluding the sound collection element determined to be in failure by the failure determination unit, and each of the sound sources can be used. And a directivity forming unit that forms the directivity of the sound in a specific direction using the delay time of the sound propagated to the plurality of sound collecting elements.

  According to this configuration, the failure detection system is configured such that during actual use, the sound collected by the plurality of usable sound collection elements excluding the sound collection element in failure and the plurality of usable collections from the sound source. Since the sound directivity can be formed in a specific direction using the delay time of the sound propagated to the sound element, it is possible to suppress deterioration of the sound directivity formation accuracy in the specific direction. .

  Further, in one embodiment of the present invention, the failure determination unit may cause the sound collection element used for comparison with the predetermined range to fail when the difference exceeds the predetermined range continuously over a plurality of times. It is a failure detection system that determines that it is in the middle.

  According to this configuration, when the difference between the individual average power for each sound collection element and the total average pattern exceeds the predetermined range over a plurality of times continuously, the failure detection system determines the sound collection element used for comparison. By determining that there is a failure, for example, an error at the time of sound collection that occurs temporarily can be eliminated, and the determination accuracy of the presence or absence of a failure of the sound collection element can be improved.

  Further, in one embodiment of the present invention, the failure determination unit is used for comparison with the predetermined range when the difference continuously exceeds the predetermined range over a plurality of times at at least one specific frequency. It is a failure detection system for determining that the sound pickup element that has been in failure is in failure.

  According to this configuration, the failure detection system performs comparison when the difference between the individual average power and the total average pattern for each sound collection element exceeds a predetermined range over a plurality of times at least at one specific frequency. By determining that the sound collecting element used in the above is in failure, it is possible to detect a failure of the sound collecting element that causes an error during sound collection depending on the specific frequency. Therefore, the failure detection system can monitor the change in the frequency characteristics of the sound collection element by monitoring the presence or absence of the failure of the sound collection element at at least one specific frequency, and can perform failure detection with high accuracy. it can.

  In one embodiment of the present invention, the failure determination unit is used for comparison with the predetermined threshold when a ratio of the difference exceeding the predetermined range in a predetermined period is equal to or greater than a predetermined threshold. It is a failure detection system for determining that the sound collection element is in failure.

  According to this configuration, in the failure detection system, the ratio of the difference between the individual average power and the total average pattern for each sound collection element in a predetermined period exceeds the predetermined range more than once more than the predetermined threshold. In some cases, by determining that the sound pickup element used for the comparison with the predetermined threshold is in failure, it is determined that the sound pickup element is defective when the frequency of occurrence of errors during sound collection is high. The accuracy of determining whether or not there is a failure can be improved. In addition, since the predetermined threshold value may be set to be changeable, the failure detection system can flexibly determine whether or not the sound pickup element has failed according to the surrounding situation where the failure detection system is installed. .

  In one embodiment of the present invention, the first calculation unit samples the sound collected by the sound collection element at predetermined time intervals, and averages the sound collected by the sound collection element. It is a failure detection system which calculates power for every said sound collection element.

  According to this configuration, the failure detection system samples the data of the sound collected by the sound collection element at predetermined time intervals and calculates the average power of the sound for each sound collection element. The more it is used, the more the reliability of the average power of the sound for each sound collecting element can be improved.

  In one embodiment of the present invention, the first calculation unit, the second calculation unit, and the failure determination unit are included in the sound collection unit, and the sound collection unit includes the sound collection element in failure. If it is determined that there is a failure, the failure data related to the sound pickup element in failure is added to the voice data packet including the sound collected by each of the sound pickup elements excluding the sound pickup element in failure. It is a failure detection system which transmits to a sex formation part or the said recorder apparatus.

  According to this configuration, since the failure detection system adds failure data regarding the sound collection element in failure to the audio data packet, for example, when reproducing recorded audio data, the audio transmitted from the sound collection unit The process of analyzing the error notification log of the data packet in detail can be omitted, and the sound collecting element in failure can be easily identified. In addition, the failure detection system can easily detect the failure of the sound collection element without analyzing the log of the recorder device no matter where the recorded voice data is played back from any point in time by the user's operation. It can be grasped and directivity can be formed using a usable sound pickup element.

  In one embodiment of the present invention, the first calculation unit, the second calculation unit, and the failure determination unit are included in the sound collection unit, and the sound collection unit includes the sound collection element in failure. In a case where it is determined that there is a voice data packet including the voice collected by each of the sound pickup elements excluding the faulty sound pickup element, the fault data packet related to the faulty sound pickup element is It is a failure detection system which transmits to a directivity formation part or the said recorder apparatus.

  According to this configuration, the failure detection system directs the failure data packet related to the sound pickup element in failure separately from the sound data packet including the sound collected by the sound pickup element excluding the sound pickup element in failure. Therefore, it is possible to easily identify the sound pickup element in failure by the failure data packet.

  Moreover, one Embodiment of this invention is a failure detection system provided with the notification part which notifies that there exists the said sound collection element in failure.

  According to this configuration, the failure detection system can notify the operator that a failure has occurred in the sound collection element.

  Moreover, one embodiment of the present invention is the failure detection system in which the notification unit notifies that there is the sound pickup element in failure by displaying a predetermined icon on the screen of the display unit.

  According to this configuration, the failure detection system can notify the operator that a failure has occurred in the sound collection element by using the predetermined icon displayed on the screen of the display unit.

  In one embodiment of the present invention, the notification unit has the sound pickup element in failure by displaying a pop-up window including information on the sound pickup element in failure on the screen of the display unit. This is a failure detection system that notifies

  According to this configuration, the failure detection system can notify the operator that a failure has occurred in the sound collection element by a pop-up window displayed on the screen of the display unit.

  In one embodiment of the present invention, the notification unit displays failure log information on the sound pickup element in failure on the screen of the display unit, thereby notifying that there is the sound pickup element in failure. This is a failure detection system.

  According to this configuration, the failure detection system can notify the operator that a failure has occurred in the sound collection element, based on the failure log information displayed on the screen of the display unit.

  In addition, an embodiment of the present invention further includes a recorder device that records audio data of the sound collected by the sound collection unit, and the recorder device has a failure in a display unit or an illumination unit of the recorder device. It is a failure detection system for displaying or lighting information on the sound pickup element during or after repair.

  According to this configuration, the failure detection system displays or turns on information about the microphone element that is in failure or has been repaired on the display unit or the illumination unit of the recorder device, so that there is a microphone element that is in failure for the operator. Or that there is a microphone element after restoration (recovered, restored) can be easily and visually notified.

  In addition, an embodiment of the present invention is a failure detection method in a failure detection system having a sound collection unit including a plurality of sound collection elements, the average power of the sound propagated from a sound source to each of the sound collection elements. Calculating for each sound collection element; calculating a total average power of the sound propagated to the plurality of usable sound collection elements included in the sound collection unit; and average power for each sound collection element And determining whether or not there is an unusable faulty sound pickup element based on a comparison result of whether or not a difference between the total average power exceeds a predetermined range. Is the method.

  In this method, the failure detection system calculates the average power of the sound propagated from the sound source to each sound collection element for each sound collection element, and further adds a plurality of usable sound collection elements included in the sound collection unit. Calculate the total average power of the propagated speech. In addition, the failure detection system determines whether or not there is an unusable sound collecting element based on a comparison result of whether or not the difference between the average power and the total average power for each sound collecting element exceeds a predetermined range. Determine whether.

  As a result, even when the failure detection system is actually in use, the acoustic characteristics of each sound collection element included in the sound collection unit (for example, the average value of the individual sound powers of the sound collection elements as the sound power, The average value of the total sound power of a plurality of sound pickup elements that can be used) is monitored. The sound collection element can be specified. Accordingly, the failure detection system suppresses deterioration of the directivity formation accuracy of the sound in a predetermined direction even when the sound collection element included in the sound collection unit is abnormal even during actual use. be able to.

  While various embodiments have been described above with reference to the drawings, it goes without saying that the present invention is not limited to such examples. It will be apparent to those skilled in the art that various changes and modifications can be made within the scope of the claims, and these are naturally within the technical scope of the present invention. Understood.

  The present invention monitors the characteristics of each microphone element included in the microphone array apparatus even during actual use, identifies the microphone element in which an abnormality has occurred, The present invention is useful as a failure detection system and a failure detection method for suppressing deterioration of the directivity formation accuracy of voice in a direction.

2, 2A to 2E, 2G Omnidirectional microphone array device 3 Directivity control device 4 Recorder device 10 Failure detection system 21, 21C, 21D, 21E Case 22, 23 Microphone unit 25 Encoding unit 26 Transmission unit 27 Error packet generation unit 29, 29A Detection unit 31 Communication unit 32 Operation unit 33 Signal processing unit 34a Directional direction calculation unit 34c Output control unit 34g Directionality formation unit 36 Display device 36A Pull-down menu list 36B Various operation buttons 36C Detailed information presentation column 36D Pop-up window 36e Equipment failure log 36f Equipment failure log list 37 Speaker device 38 Memory 39 Adder 41 Icon 80 Sound source 221, 222, 223, 22i, 22n Microphone elements 241, 242, 243, 24i, 24n A / D converters 251, 252, 253, 2 n delayer 281,28i, 28n amplifier (amplifier)
331 FFT unit 335 Directivity processing unit 336 Inverse FFT unit 337 Judgment unit 340, 350, 360 Failure detection unit 341, 351, 361 Smoothing unit 342, 352, 362 Comparison unit 343, 353, 363 Average calculation unit 345, 355, 365 Result holding unit 381 Usable microphone information holding unit 382 Log information holding unit C11 Camera device

Claims (13)

A sound collection unit including a plurality of sound collection elements;
A first calculator that calculates, for each sound collection element, an average power of sound propagated from a sound source to each of the sound collection elements;
A second calculation unit that calculates the total average power of the sound propagated to the plurality of usable sound collection elements included in the sound collection unit;
Based on the comparison result of whether or not the difference between the average power for each of the sound pickup elements and the total average power exceeds a predetermined range, it is determined whether or not there is a sound pickup element in use that is not usable. A failure determination unit ,
The first calculation unit includes:
Sampling the audio picked up by the microphone element at predetermined time intervals, that to calculate the average power of the sound collected by the sound collecting device for each of the sound collection device,
Fault detection system. The failure detection system according to claim 1,
The sound collected by a plurality of usable sound collection elements excluding the sound collection element determined to be in failure by the failure determination unit, and transmitted from the sound source to each of the plurality of usable sound collection elements. Further comprising a directivity forming unit that forms the directivity of the voice in a specific direction using the delay time of the voice.
Fault detection system. The failure detection system according to claim 1,
The failure determination unit
When the difference exceeds the predetermined range continuously several times, it is determined that the sound collection element used for comparison with the predetermined range is in failure.
Fault detection system. The failure detection system according to claim 1,
The failure determination unit
When the difference exceeds the predetermined range continuously over a plurality of times at at least one specific frequency, it is determined that the sound pickup element used for comparison with the predetermined range is in failure.
Fault detection system. The failure detection system according to claim 1,
The failure determination unit
When the ratio that the difference exceeds the predetermined range in a predetermined period is equal to or greater than a predetermined threshold, it is determined that the sound collection element used for comparison with the predetermined threshold is in failure.
Fault detection system. The failure detection system according to claim 2,
A voice recording unit that records voice data of the voice collected by the sound collecting unit;
The first calculation unit, the second calculation unit, and the failure determination unit are included in the sound collection unit,
The sound collection unit is
When it is determined that there is a sound collecting element in failure, the sound including sound collected by each sound collecting element other than the sound collecting element in failure is included in the failure data related to the sound collecting element in failure. Add to the data packet and send to the directivity forming unit or the voice recording unit,
Fault detection system. The failure detection system according to claim 2,
A voice recording unit that records voice data of the voice collected by the sound collecting unit;
The first calculation unit, the second calculation unit, and the failure determination unit are included in the sound collection unit,
The sound collection unit is
When it is determined that there is the sound collecting element in failure, the sound collecting element in failure is separated from the voice data packet including the sound collected by each sound collecting element except the sound collecting element in failure. Transmitting a failure data packet relating to a sound element to the directivity forming unit or the voice recording unit;
Fault detection system. The failure detection system according to claim 1,
A notification unit for notifying that there is the sound pickup element in failure;
Fault detection system. The failure detection system according to claim 8 ,
The notification unit
Notifying that there is the sound pickup element in failure by displaying a predetermined icon on the screen of the display unit,
Fault detection system. The failure detection system according to claim 8 ,
The notification unit
Notifying that there is the sound pickup element in failure by displaying a pop-up window including information on the sound pickup element in failure on the screen of the display unit,
Fault detection system. The failure detection system according to claim 8 ,
The notification unit
Notifying that there is the sound pickup element in failure by displaying failure log information on the sound pickup element in failure on the screen of the display unit,
Fault detection system. The failure detection system according to claim 1,
A recorder device for recording voice data of the voice collected by the sound collection unit;
The recorder device
In the display unit or the lighting unit of the recorder device, information on the sound pickup element during or after failure is displayed or lit.
Fault detection system. A failure detection method in a failure detection system having a sound collection unit including a plurality of sound collection elements,
Calculating the average power of the sound propagated from the sound source to each of the sound collection elements for each sound collection element;
Calculating the total average power of the sound propagated to the plurality of usable sound collection elements included in the sound collection unit;
Based on the comparison result of whether or not the difference between the average power for each of the sound pickup elements and the total average power exceeds a predetermined range, it is determined whether or not there is a sound pickup element in use that is not usable. and the step, the possess,
In the step of calculating the average power of the sound, the sound collected by the sound collecting element is sampled at predetermined time intervals, and the average power of the sound collected by the sound collecting element is sampled. Calculate every time ,
Failure detection method.

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